Osseointegration of multiphase anodic spark deposition treated porous titanium implants in an ovine model.

Modification of titanium oxide by multiphase anodic spark deposition (ASD) has the potential to increase bioactivity and hasten osseointegration and biological fixation in uncemented arthroplasty. This study assessed the in vivo performance of control (Ti), plasma-sprayed HA-coated (TiHA) and ASD (Biospark) treated (TiAn) porous titanium implants with a solid core using a standard uncemented implant fixation sheep model. Cortical interfacial shear-strength and bone ingrowth in cortical and cancellous sites were quantified following 12 weeks in situ. Ultimate shear-strength for the Ti, TiHA and TiAn coatings was 33±9.5, 35.4±8.4 and 33.8±7.8 MPa, respectively, which was limited by coating delamination. ASD treatment was associated with significantly higher mean bone ingrowth at both sites. These results support the osteoconductive potential of the BioSpark treatment of porous titanium.

Wear of a composite ceramic head caused by liner fracture.

Third-generation composite ceramics (eg, Delta; DePuy Orthopaedics, Warsaw, Indiana; Ceramtec, Plochingen, Germany) have greatly improved material characteristics compared with second-generation products. This case report presents a patient after total hip arthroplasty with a fractured ceramic liner and a heavily worn ceramic head (both third-generation ceramics) retrieved 9 months after surgery. The patient showed no symptoms in the involved hip but presented to the hospital because of other symptoms. The failure was caused by a tilted liner that was overlooked after surgery and fractured consecutively. Rim chipping and splitting were the 2 fracture modes observed for the liner. The head did not fracture completely because of its high strength but became roughened by the ceramic fragments, causing major wear of the metal back of the cup. The phase transformation of the zirconium grains from tetragonal to monoclinic in the aluminum oxide matrix was shown by radiographic diffraction analysis in the heavily worn areas of the head. This transformation increases the fracture strength of the head. Metal debris caused by a roughened ceramic head without fracture is an unreported phenomenon for third-generation ceramic bearings in hip arthroplasty. This case shows that proper impaction of the ceramic liner into the metal shell to prevent later tiling during reduction is as important as correct component positioning. If a tilted ceramic liner is observed postoperatively, the position must be corrected immediately to prevent the major consequences observed in this patient.

Comminuted periprosthetic humeral fracture after reverse shoulder prosthesis.

Periprosthetic fractures represent a severe complication after joint replacement. A case of comminuted displaced humeral fracture around the stem of a SMR reverse shoulder prosthesis is reported. The patient was a 81-year-old lady who had had a total shoulder replacement 28 months previously. The surgical solution consisted of a partial revision of the modular implant with conservation not only of the glenoid component but also of the prosthetic humeral body, which was well fixed in the humeral metaphysis. The humeral stem was removed and a long uncemented revision stem was implanted providing fracture stabilisation and allowing early mobilisation.

Anodic Spark Deposition treatments to increase reliability of Ti6Al4V modular prostheses.

PURPOSE: The aim of this study was to evaluate whether an Anodic Spark Deposition treatment, which assures increased resistance of titanium alloys to fretting corrosion, improves the structural reliability of Ti6Al4V modular hip prostheses, thus preventing the recently noticed in vivo mechanical failures of these components due to fatigue events. METHODS: Three commercial treatments were tested in this work. Microhardness, roughness and fatigue resistance measurements were carried out to investigate the treatment performances. RESULTS: The experimental tests showed that the implant responded differently based on the treatment. The treatment that assured the best performances induced an increase in fatigue resistance with respect to the initial properties of the non-treated Ti6Al4V alloy. CONCLUSIONS: Since in previous research the same surface treatment was shown to prevent fretting corrosion phenomena, the study tests confirmed that the Anodic Spark Deposition treatment can significantly increase the structural reliability of Ti6Al4V multi-component prostheses.